Any discussion of documents, acts, materials, devices, articles or the like which has been included in this specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed in Australia or elsewhere before the priority date of this application.
Prior art transit units are known whereby services, such as cables, pipes, etc., are routed through barriers (for example walls, floors, ceilings and service shafts), in a manner that provides a degree of passive fire protection. It is desirable for such transit units to exhibit integrity characteristics (i.e. where the product provides resistance to the passage of flames or hot gasses for a predetermined time) and insulation characteristics (i.e. where one side of the product is exposed to an elevated temperature and the other side of the product must not exceed a pre-determined temperature rise within a predetermined time). It has been appreciated by the inventor of the present application that typical prior art transit units, such as the Abesco CT120 and CT240 cable transit units for example, perform relatively well in relation to the integrity characteristics; however, they typically perform fairly poorly in relation to the insulation characteristics.
In an attempt to improve the insulation characteristics of the prior art units, it is known to apply a thermally non-conducting wrap to the transit units and the services passing there through. These are held in place with steel strapping that is mechanically fixed in a permanent manner. However, it has been appreciated by the inventor of the present application that this approach suffers from draw backs when attempting to retro-fit additional services through the transit unit (i.e. at some later time after the initial installation has been completed). In particular, the wrap material must be cut off and replaced with a new wrap system and new steel strapping requiring the use of specialised tools each time the services passing through the transit unit are to be altered.